christexaport is perfectly right with his observation, but still I doubt there's something going on that Google is responsible for.

I too noticed that a lot of articles (and even reviews!) of the N900 come view N810-pictures. Remember the review in a German magazine that was discussed here recently? They had an N900 to play with, they even published a video, but still in their ranking list they used the image of an N810.

I don't know why such things happen, but they do. And because there's a lot more N900-related content now than weeks ago when the "pink flower"-image dominated, it's only logical that results look different now.